In a mobile communication system, a plurality of mobile terminals can make radio communication with a base station, using the identical frequency.
When the base station performs radio communication with a certain mobile terminal, the quality of reception is deteriorated if the received signal (the desired signal) that is received from the mobile terminal is interfered with by a received signal (the interference signal) that is received from another mobile terminal.
As one example of an interference removal technology for removing such interference signals, there is a technology in which an antenna is formed of a plurality of antenna elements so that the received signals at individual antenna elements are antenna-combined to control the antenna directivity (see Patent Document 1). According to this, the antenna directivity is controlled so that a null is formed in the direction of an interference signal, whereby the interference signal can be removed.